Can't change permissions for header.php

Can't change permissions for header.php

Here is my official WordPress forum support plea:
http://wordpress.org/support/topic/headerphp-is-not-updating?replies=4
I changed all the permissions via FTP, currently set to 777. Originally
666, but that didn't work, so here we are.
I cleared all of my browser caches.
I added:
define('DISABLE_CACHE', true);
to wp-config.php
I don't know what else to do at this point. The file on my server reflects
the changes I made, but if you look at the source on the website, via
Firebug or whatever, it isn't there.
From the native WordPress editor, it says I can't edit the file because
the permissions aren't set. What's really absurd is that this is a custom
theme specifically for this website. Whose business is it if I want to
change it?
Can anyone please at least verify that the correct 'header.php' is in
wp-content/themes/themeofchoice?
I greatly appreciate any assistance.